Unknown White Compound 643p Lab Report

Identification and Recreation of Unknown White Compound #643p
November 13, 2012

INTRODUCTION:
The identity of the unknown solid white compound is determined and verified through a series of tests which uncover physical and chemical properties necessary for identification. A new sample of the same compound is then created to further prove the accuracy of the identification. The compound must be identified in order to be used. For example, KCl is used in medicine, scientific applications, and food processing. It also tastes a lot like sodium chloride, and is the main ingredient in dietary salt substitutes.1 The other possible compounds substance 634p could be have very different properties and uses though they look similar. Almost all
Five grams of the unknown solid white compound 643p were attained. To determine a basic physical property of the compound, a solubility test was performed in a test tube by mixing a 0.1g sample (massed on weigh paper on a scale) of the compound with a 1 mL of distilled water (measured and poured from 10 mL graduated cylinder).
Reactivity. To determine some chemical properties of the compound, precipitate tests were performed. Aqueous solutions of the compound, each made with 1 mL distilled water and 0.1 g 643p, were mixed in test tubes with aqueous solutions of AgNO3(1 mL of 0.1 M), NaCO3(1 g in 1 mL H2O) and BaCl2 (1mL of 0.2 M)to determine the reactivity of the compound 643p with each compound. These tests were also performed on solutions of possible compounds that the 643p could be, in the same way, to determine which possible compound reacted and did not react with the compounds 643p did and did not react with respectively.
Flame Color. Next, flame tests were conducted with a solution of 0.1 g 643p in l mL distilled H2O and samples of the remaining possible compounds with the same concentration. A wire loop was cleaned and dipped into the solution and held over the hottest part of the flame of a Bunsen burner. This procedure was completed for the each solution, cleaning the wire loop between each test to avoid contamination and recording and photographing each flame color and
This calculation was used to determine volume of 6 molarity KOH and 6 molarity HCl needed to synthesize 1 gram of KCl:

These chemicals combined in the acid-base reaction:
KOH (aq) + HCl (aq) KCl (aq) +H2O (l)
The respective volumes of each solution were measured out in graduated cylinders and combined in a large beaker (to increase surface area for evaporation). With added heat to speed up the process, the water dissolved off leaving only the white powdery solid KCl. 0.937 g of substance was the final mass which since the theoretical yield was 1 g gave a 93.7% yield. Some KCl was likely evaporated with the water and some was likely lost in transferring from the beaker to the watch glass, so a 93.7% yield is adequate.
Proof. The synthesized compound looked just like KCl, only a little clumpier (perhaps due to clinging water molecules) as seen in image 2.
Conductivity, pH, precipitate, and flame tests done on the synthesized compound prove consistent with KCl. Conductivities and pH were within normal deviation of similar solutions, the same precipitate reaction occurred with AgNO3, and flame colors matched, as shown below in images 3 and